Fix no / safety

isort/main.py

@@ -347,6 +347,12 @@ def _build_arg_parser() -> argparse.ArgumentParser:
         dest="filename",
         help="Provide the filename associated with a stream.",
     )
+    target_group.add_argument(
+        "--no-preserve-root",
+        action="store_true",
+        default=False,
+        help="Tells isort not to treat / specially, allowing it to be ran on the root dir.",
+    )
 
     output_group.add_argument(
         "-a",
@@ -1000,6 +1006,7 @@ def main(argv: Optional[Sequence[str]] = None, stdin: Optional[TextIOWrapper] =
     remapped_deprecated_args = config_dict.pop("remapped_deprecated_args", False)
     stream_filename = config_dict.pop("filename", None)
     ext_format = config_dict.pop("ext_format", None)
+    no_preserve_root = config_dict.pop("no_preserve_root", None)
     wrong_sorted_files = False
     all_attempt_broken = False
     no_valid_encodings = False
@@ -1037,11 +1044,18 @@ def main(argv: Optional[Sequence[str]] = None, stdin: Optional[TextIOWrapper] =
                 file_path=file_path,
                 extension=ext_format,
             )
+    elif "/" in file_names and not no_preserve_root:
+        printer = create_terminal_printer(color=config.color_output)
+        printer.error("it is dangerous to operate recursively on '/'")
+        printer.error("use --no-preserve-root to override this failsafe")
+        sys.exit(1)
     else:
         if stream_filename:
             printer = create_terminal_printer(color=config.color_output)
             printer.error("Filename override is intended only for stream (-) sorting.")
             sys.exit(1)
+        if file_names == ["/"]:
+            input("You've requested to run isort against your entire computer (/) are you sure? ")
         skipped: List[str] = []
         broken: List[str] = []